Bump OS v1.8-20260312

[harvesterhci-io-github-bot]

Problem:
Harvester base OS needs to update.

Solution:
Bump OS image to rancher/harvester-os:v1.8-20260312.

Related Issue:

Test plan:

More info:

-----RPM-----

Packages found only in docker.io/rancher/harvester-os:sle-micro-head: None

Packages found only in docker.io/rancher/harvester-os:v1.8-20260312: None

Version differences:
PACKAGE                   IMAGE1 (docker.io/rancher/harvester-os:sle-micro-head)        IMAGE2 (docker.io/rancher/harvester-os:v1.8-20260312)
-elemental-toolkit        1.1.8-160000.6.5, 20M                                         1.1.8-160000.7.1, 20M
-fio                      3.38-160000.4.8, 9M                                           3.38-160000.5.1, 9M
-iotop                    0.6git.20230403-160000.4.7, 213.1K                            0.6git.20230403-160000.5.1, 213.1K
-k9s                      0.50.18-160000.4.6, 135.5M                                    0.50.18-160000.5.1, 135.5M
-kubevirt-virtctl         1.7.0-160000.11.5, 67.8M                                      1.7.0-160000.12.1, 67.8M
-tcpdump                  4.99.5-160000.2.6, 1.4M                                       4.99.5-160000.3.1, 1.4M
-yip                      1.6.2-160000.2.14, 16.9M                                      1.6.2-160000.3.1, 16.9M
-yq                       4.52.2-160000.52.5, 15.2M                                     4.52.2-160000.53.1, 15.2M